1). Field of the Invention
This invention relates to a system for testing and burning in of integrated circuits of an unsingulated wafer.
2). Discussion of Related Art
Integrated circuits, such as circuits with metal-oxide-semiconductor (MOS) transistors or laser diodes, are usually manufactured in and on wafer substrates. Such a wafer substrate is then “diced” or “singulated” into individual dies, each die having a respective integrated circuit. The die can then be mounted to a supporting substrate for purposes of providing rigidity to the die and for providing power, a ground reference voltage and signals to or from the integrated circuit in the die.
Integrated circuits are usually tested and burned in before being shipped to a customer. It is desirable to identify defective integrated circuits at an early stage for purposes of determining where defects typically occur and for reducing downstream manufacturing and packaging costs. Ideally, some testing is carried out before a wafer is singulated. Burn-in may be performed to induce devices with latent defects to fail, which otherwise would not occur until the integrated circuit had been in use for some time.
Relatively complex prober-based systems have traditionally been used for burn-in testing of integrated circuits at wafer level. Such a system typically has probe contacts and a relatively complex mechanism that can move a wafer in x-, y- and z directions so that die contacts on successive integrated circuits are brought into contact with the probe contacts. A test sequence is provided through the probe contacts to each integrated circuit while being exposed to a predetermined temperature profile.
Certain advances have been made in recent years to simultaneously contact die contacts of integrated circuits of an entire unsingulated wafer, often referred to as “full wafer probing,” and then test the integrated circuits of the entire wafer. A system that is used for burn-in or testing integrated circuits of an array of dies of an unsingulated wafer usually has a distribution board for distributing power, a ground reference voltage, and signals in x- and y-directions to distribution board contacts that mirror the die contacts over an x-y area on the wafer substrate. A contactor board is located between the distribution board and the wafer, the contactor board having contactor pins that interconnect the distribution board contact terminals in a z-direction with the die contacts.
For performing burn-in, such a system together with the unsingulated wafer can then be inserted into a thermal management system such as an oven. An interface on the distribution board connects to a connector in the oven so that power, a ground reference voltage and signals can be provided through the connector, the distribution board and the contactor board to or from the integrated circuits. The integrated circuits undergo burn-in testing while the temperature of the wafer is controlled.